This invention relates to a novel method of packaging a chemical type thermometer which makes it usable as an axillary thermometer. The term "chemical thermometer" as used in the specification and claims means the prior art non-mercury thermometers which depend on the melting or change of state of a thermally responsive material for temperature indication. The term includes liquid crystal thermometers as well as thermometers which produce a signal utilizing a chemical compound melting at a predetermined temperature. A commercial thermometer of the latter type is sold under the trademark TEMPA.DOT.RTM. by Pymah Corporation.
U.S. Pat. No. 3,946,612 to Sagi, 3,956,153 to Chadha and 3,980,581 to Godsey, all of which are incorporated herein by reference, disclose a chemical thermometer utilizing solid solutions of ortho-chloronitrobenzene and ortho-bromonitrobenzene as the temperature responsive composition melting at a predetermined temperature. The thermometer of those patents comprises a substrate which has been embossed to accept the temperature sensitive composition. The composition has incorporated therein a nucleating agent which is preferably anthraquinone. A clear cover layer is disposed over the substrate, the cover layer having indicating dots of paper containing a dye layer, disposed on the cover layer so as to fit into the embossments. When the indicating chemical melts it is wicked up through a first layer of paper into a dye containing layer, and subsequently, through an upper layer so that the signal can be observed. In order to prevent "firing" as a result of temperature excursions the substrate and the cover layer are separated from one another until use. A plastic, pressure sensitive adhesive coated film is adhered to both the substrate and the cover layer. At the time of use the plastic film is stripped away in a manner so as to bring together the cover strip and substrate with the indicating paper dots in juxtaposition with the embossed pockets. See for example U.S. Pat. Nos. 3,712,141 to Chadha, and 3,677,088 to Lang, both incorporated herein by reference for a description of the mechanism for accomplishing this result. U.S. Pat. No. 3,677,866, to Pickett, et al., incorporated herein by reference, discloses a package for utilizing the thermometer device of Lang '088.
An improved disposable thermometer utilizing the solid solutions of Sagi, '612, is disclosed in U.S. Pat. No. 4,232,552, to Hof, incorporated herein by reference. The Hof device eliminates the nucleating agent so that the signal obtained will remain for a time sufficient to read the thermometer. A dye, or combination of dyes, is incorporated into the solid solution the solid solution/dye system exhibits a first color when the solid solution is in the solid state and a second color when the solid solution is in the liquid state.
In an earlier version of chemical thermometers, U.S. Pat. No. 3,465,590, to Kluth discloses a device wherein the embossments are filled with fatty acid material which are opaque in the solid state, but transparent when melted. The embossment has a color or number message in the bottom which becomes visible when the fatty acid is melted.
Another embodiment of the chemical thermometers of the prior art is the liquid crystal thermometer. This embodiment utilizes cholestryl liquid crystals which change color in response to temperature changes. See for example U.S. Pat. Nos. 3,974,317 and 4,064,822 incorporated herein by reference. Liquid crystal thermometers have been utilized as thermometers for infants by applying an adhesive to the back of the thermometer and applying it to the forehead.
The above described chemical thermometers are illustrative, non-limiting examples of such thermometers. The chemical thermometers, per se, are admitted prior art.
With the exception of the liquid crystal thermometer designed as a "patch" with adhesive backing, these thermometer were designed to be oral thermometers. Some have been adapted for use as rectal thermometers, by utilizing a special adapter. Others, have been utilized as axillary thermometers. For example, the thermometer of Hof has been utilized as an axillary thermometer by taping under the arm using transparent adhesive tape. This method has the disadvantage of being a makeshift approach which can result in poor placement of the thermometer or inadequate contact with the axillary area. What is needed, and forms the basis of this invention, is a more certain method of utilizing the oral chemical thermometers of the prior art as axillary thermometers.